Relay circuit



Feb. 11, 1964 w s 3,121,189

RELAY CIRCUIT File d Feb. 5, 1962 A 6 I 2 5 STEP I O FUNCTION i 7/ I :Q) I l l l I RESET OL 2 A INVENTOR.

LAWRENCE W. MILLS United States Patent 3,121,189 RELAY CIRCUIT Lawrence W. Mills, Orange County, Fla., assignor to Martin-Marietta Corporation, Middle River, Md., a corporation of Maryland Filed Feb. 5, 1962, Ser. No. 171,047 3 Claims. (Cl. 317-.137)

not capable of energizing a large relay with a plurality of contacts. In addition, the use of a low power source to energize the relay simplifies the driving source.

One example of such an application is a receiver for a communication system in which messages are transmitted in pulse codes to the receiver. It is desirable to enable a decoder when input pulses are received. These pulses are detected and integrated to provide a low power step function for driving a relay. Such a system is shown in the U.S. patent application entitled Discrete Address Communication System With Random Address Capabilities, filed May 2, 1961, Serial No. 107,194, inventor Mc- Kay Goode, and assigned to the assignee of the present invention.

Accordingly it is an object of the present invention to provide an improved relay circuit which is actuated in response to the occurrence of a low power step function.

It is a further object of the present invention to provide a relay circuit in which a first relay having a high impedance actuating winding and a single set of contacts is actuated in response to low power input pulses and in which this first relay supplies energizing power through its single set of contacts to a second relay having a plurality of contacts and to the actuating winding of the first relay so as to hold the first relay.

In accordance with one embodiment of the invention the low power step function input is connected to energize one end of the actuating winding of a first relay. This first relay has a high impedance winding and can be actuated by a very low power source. The first relay carries a single set of contacts. A source of energizing power is connected through this first set of contacts and through a diode to the first end of the actuating winding of the relay. When the relay is actuated by the triggering step function, the contact is closed and the energizing power is supplied to hold this relay.

The source of energizing power is also connected through the single set of contacts of the first relay to the actuating winding of a second relay. When the first relay is actuated by the input pulses, energizing power is supplied to the actuating winding of the second relay which can actuate any number of sets of contacts to perform any necessary switching functions.

These and other objects, advantages and features of the present invention Will be more apparent from the following detailed description together with the appended claims and the single drawing which shows a preferred embodiment of this invention.

Referring now to the drawing the step function is connected through diode 2 to the actuating winding 3 of the first relay. The diode 2 is provided to isolate the inputcircuit from the remainder of the relay circuitry when relay 3 is in the latched condition. This winding has a very high impedance and the relay carries only a single set of contacts 4. Relays of this type may be actuated from a very low power source. One example of a relay 3,121,189 Patented Feb. 11, 1964 particularly suitable for this purpose is a Neomite Ultra- Miniature D.C. Relay, NM/ lC/ZK.

In order to hold the first relay when it is actuated and in order to energize a second relay which carries the switching contacts, a source of power 6 is connected through the set of contacts -4. This source of power may be connected through the normally closed set of contacts to any devices which are to be de-energized upon the occurrence of an input step function. The source of power 6 is also connected through the normally open set of contacts 4 and through the diode 5 to the actuating winding 3. The diode 5 is poled in a forward direction with respect to the source of power 6 but is poled in a reverse direction with respect to the input step function.

When the step function generator 1 produces a positive output, the diode 5 blocks this positive voltage and insures that all of the power in the step function is used to energize the winding 3.

The positive source of power 6 is also connected through normally open contacts 4 to the actuating winding 7 of a second relay. This relay is of the heavy duty type and carries a number of sets of contacts, the sets 8 and 9 being shown. When the relay winding 3 is energized in response to the detection and integration of a small number of input pulses, or a step function, the normally open set of contacts 4 is closed thereby supplying positive power to the winding 3 to hold this relay and supplying power to the winding 7 to actuate the second relay and perform the necessary switching functions.

In order to indicate the actuation of the relay circuit, an indicating lamp '10 is provided. This lamp is energized by the source of power 6 which is supplied to the lamp through the normally open set of contacts 4. It is important that the lamp is not connected across the actuating winding 3 as in many prior art relay circuits. In relay circuits of that type, the indicating lamp shunts the relay Winding thereby presenting a low impedance to the source of input pulses. This makes it difiicult to actuate the relay circuit from a low power source.

In order to reset the relay circuit, a reset switch 11 is provided. This switch is connected in the circuit between the actuating windings 3 and 7 and ground. The relay windings 3 and 7 are normally energized through the contacts of switch 11. When this switch is depressed, thereby breaking this connection, the relays 3 and 7 are released. Provision may be made to lock the switch 11 in the open condition thereby preventing actuation of the relay circuit.

The operation of the relay circuit is as follows: A 10 volt positive step function from the source -1 is applied to diode 2, thereby forward biasing diode 2. Diode 2 provides a conducting path through winding 3 and switch 11. The junction of diode 2. and winding 3 is positive during the occurrence of the positive step function. Therefore, diode S is back-biased. Energization of winding 3 closes contact 4 and supplies a 12 volt positive voltage to forward bias diode 5. Since the 12 volts from the source 6 is more positive than the step function from the source 1, the diode 2 is back-biased.

The plus 12. volts from the source 6 supplies current through the contact 4, diode 5, winding 3, and reset switch 11, thereby holding the winding 3. The winding 3 is maintained in an energized condition even though the input step function at diode 2 no longer exists. While the relay is in the latched condition, the diode 2 is back-biased to any further input step function under 12 volts in amplitude, such as the 10 volt step function described. Power is supplied to any additional circuitry such as solenoid 7 and indicator 10 through the closed contact 4.

While a particular embodiment of the invention has been shown and described, it will, of course, be understood that various other modifications may be made without departing from the principles of the invention. The appended claims are, therefore, intended to cover any such modifications within the true spirit and scope of the invention.

I claim:

1. A relay circuit which can be energized by a low power input voltage comprising a first relay having an actuating winding and a single normally open set of contacts, a first diode, said first diode being connected between a source of input voltage and a first end of the actuating 'winding of said first relay, said diode being poled in the forward direction with respect to said input voltage, the second end of the actuating winding of said first relay being connected to ground, a source of energizing voltage, a second diode, said source of energizing voltage being connected through said set of normally open contacts to one electrode of said second diode, the other electrode of said second diode being connected to said first end of the actuating winding of said first relay, said second diode being poled in the forward direction with respect to said source of energizing voltage and in the reverse direction with respect to said input voltage, a see second relay, the other end of the actuating winding of said second relay being connected to ground.

2. The relay circuit recited in claim 1 and a reset switch, said reset switch being connected between the second ends of the actuating windings of said first and said second relays and ground, said reset switch being normally closed, said reset switch being adapted to release said first and said second relays when said switch is opened. 3. The relay circuit recited in claim \1 and an indicating lamp, said source of energizing voltage being connected to said indicating lamp through said normally open set of contacts.

References Cited in the file of this patent UNITED STATES PATENTS 2,759,130 Brewer Aug. 14, 1956 2,761,998 Chen Sept. 4, 1956 3,029,369 Lang Apr. 10, 196-2 

1. A RELAY CIRCUIT WHICH CAN BE ENERGIZED BY A LOW POWER INPUT VOLTAGE COMPRISING A FIRST RELAY HAVING AN ACTUATING WINDING AND A SINGLE NORMALLY OPEN SET OF CONTACTS, A FIRST DIODE, SAID FIRST DIODE BEING CONNECTED BETWEEN A SOURCE OF INPUT VOLTAGE AND A FIRST END OF THE ACTUATING WINDING OF SAID FIRST RELAY, SAID DIODE BEING POLED IN THE FORWARD DIRECTION WITH RESPECT TO SAID INPUT VOLTAGE, THE SECOND END OF THE ACTUATING WINDING OF SAID FIRST RELAY BEING CONNECTED TO GROUND, A SOURCE OF ENERGIZING VOLTAGE, A SECOND DIODE, SAID SOURCE OF ENERGIZING VOLTAGE BEING CONNECTED THROUGH SAID SET OF NORMALLY OPEN CONTACTS TO ONE ELECTRODE OF SAID SECOND DIODE, THE OTHER ELECTRODE OF SAID SECOND DIODE BEING CONNECTED TO SAID FIRST END OF THE ACTUATING WINDING OF SAID FIRST RELAY, SAID SECOND DIODE BEING POLED IN THE FORWARD DIRECTION WITH RESPECT TO SAID SOURCE OF ENERGIZING VOLTAGE AND IN THE REVERSE DIRECTION WITH RESPECT TO SAID INPUT VOLTAGE, A SECOND RELAY, SAID SECOND RELAY HAVING AN ACTUATING WINDING AND A PLURALITY OF SETS OF CONTACTS, SAID SOURCE OF ENERGIZING VOLTAGE BEING CONNECTED THROUGH SAID SET OF NORMALLY OPEN CONTACTS TO ONE END OF THE ACTUATING WINDING OF SAID SECOND RELAY, THE OTHER END OF THE ACTUATING WINDING OF SAID SECOND RELAY BEING CONNECTED TO GROUND. 